Dynamic laser power control in light detection and ranging (lidar) systems

ABSTRACT

Embodiments of the disclosure provide a system for controlling power of laser lights emitted by an optical sensing device. The system includes at least one storage device configured to store instructions and at least one processor communicatively coupled to the at least one storage device and configured to execute the instructions to perform operations. The operations include detecting an object within a field of view of the optical sensing device based on a reflected laser signal received by the optical sensing device, determining a distance of the object from the optical sensing device, determining a value indicating a total power of one or more laser beams to be incident on an aperture at the distance, and comparing the value with a predetermined tolerance value. The operations also includes adjusting a laser emission scheme to reduce the total power when the value is greater than the predetermined tolerance value.

TECHNICAL FIELD

The present disclosure relates to Light Detection and Ranging (LiDAR)systems, and more particularly to, systems and methods for dynamic laserpower control in the LiDAR systems.

BACKGROUND

Optical sensing systems such as LiDAR systems have been widely used inautonomous driving and producing high-definition maps. For example, atypical LiDAR system measures the distance to a target by illuminatingthe target with pulsed laser light beams and measuring the reflectedpulses with a sensor such as a photodetector. Differences in laser lightreturn times, wavelengths, and/or phases can then be used to constructdigital three-dimensional (3D) representations of the target. Becauseusing a narrow laser beam as the incident light can map physicalfeatures with very high resolution, a LiDAR system is particularlysuitable for applications such as sensing in autonomous driving and/orhigh-definition map surveys.

A LiDAR system can use a transmitter to transmits a signal (e.g., pulsedlaser light) into the surroundings, and use a receiver to collect thereturned signal (e.g., laser light reflected by an object in thesurroundings). The LiDAR system can then calculate parameters such asthe distance between the object and the LiDAR system based on, e.g., thespeed of light and the time the signal travels (e.g., the duration oftime between the time the signal is transmitted and the time thereturned signal is received) and use the parameters to construct 3D mapsand/or models of the surroundings. To improve the detection range andthe signal-to-noise-ratio (SNR), higher energy of the laser light isoften needed. On the other hand, however, the energy of the signal alsoneeds to be limited to avoid potential harm to human eye. Therefore, itis challenging to balance the performance demands and regulatory safetymandate in LiDAR system development.

Embodiments of the disclosure address the above challenges by systemsand methods for dynamically controlling the laser power used in LiDARsystems.

SUMMARY

Embodiments of the disclosure provide a system for controlling power oflaser lights emitted by an optical sensing device. The system mayinclude at least one storage device configured to store instructions andat least one processor communicatively coupled to the at least onestorage device and configured to execute the instructions to performoperations. The operations may include detecting an object within afield of view of the optical sensing device based on a reflected lasersignal received by the optical sensing device, determining a distance ofthe object from the optical sensing device, determining a valueindicating a total power of one or more laser beams to be incident on anaperture at the distance, and comparing the value with a predeterminedtolerance value. The operations may also include adjusting a laseremission scheme to reduce the total power when the value is greater thanthe predetermined tolerance value.

Embodiments of the disclosure also provide a method for controllingpower of laser lights emitted by an optical sensing device. The methodmay include detecting an object within a field of view of the opticalsensing device based on a reflected laser signal received by the opticalsensing device, determining a distance of the object from the opticalsensing device, and determining a value indicating a total power of oneor more laser beams to be incident on an aperture at the distance. Themethod may also include comparing the value with a predeterminedtolerance value and adjusting a laser emission scheme to reduce thetotal power when the value is greater than the predetermined tolerancevalue.

Embodiments of the disclosure also provide a non-transitorycomputer-readable medium having instructions stored thereon. Whenexecuted by at least one processor, the instructions can cause the atleast one processor to perform a method for controlling power of laserlights emitted by an optical sensing device. The method may includedetecting an object within a field of view of the optical sensing devicebased on a reflected laser signal received by the optical sensingdevice, determining a distance of the object from the optical sensingdevice, and determining a value indicating a total power of one or morelaser beams to be incident on an aperture at the distance. The methodmay also include comparing the value with a predetermined tolerancevalue and adjusting a laser emission scheme to reduce the total powerwhen the value is greater than the predetermined tolerance value.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of an exemplary vehicle equippedwith a LiDAR system, according to embodiments of the disclosure.

FIG. 2A illustrates a block diagram of an exemplary LiDAR system,according to embodiments of the disclosure.

FIG. 2B illustrates a block diagram of an exemplary controller forcontrolling laser power in a LiDAR system, according to embodiments ofthe disclosure.

FIG. 3A illustrates detection of objects in a field of view of anexemplary LiDAR system, according to embodiments of the disclosure.

FIGS. 3B-3D each illustrates an exemplary laser emission scheme,according to embodiments of the disclosure.

FIGS. 4A and 4B illustrate a plurality of exemplary laser emissionschemes in multi-pulse ranging operations, according to embodiments ofthe disclosure.

FIG. 5 illustrates a flowchart of an exemplary method to control laserpower in a LiDAR system, according to embodiments of the disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary embodiments,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

FIG. 1 illustrates a schematic diagram of an exemplary vehicle 100equipped with a LiDAR system 102, according to embodiments of thedisclosure. As illustrated in FIG. 1, vehicle 100 may be equipped withLiDAR system 102 mounted to body 104 via a mounting structure 108.Mounting structure 108 may be an electro-mechanical device installed orotherwise attached to body 104 of vehicle 100. In some embodiments ofthe present disclosure, mounting structure 108 may use screws,adhesives, or another mounting mechanism. It is contemplated that themanners in which LiDAR system 102 can be equipped on vehicle 100 are notlimited by the example shown in FIG. 1 and may be modified depending onthe types of LiDAR system 102 and/or vehicle 100 to achieve desirable 3Dsensing performance.

Consistent with some embodiments, LiDAR system 102 may be configured tocapture data as vehicle 100 moves along a trajectory. For example, atransmitter of LiDAR system 102 is configured to scan the surroundingand acquire point clouds. LiDAR system 102 measures distance to a targetby illuminating the target with pulsed laser light and measuring thereflected pulses with a receiver. The laser light used by LiDAR system102 may be ultraviolet, visible, or near infrared. In some embodimentsof the present disclosure, LiDAR system 102 may capture point clouds. Asvehicle 100 moves along the trajectory, LiDAR system 102 maycontinuously emit/scan laser beams and receive returned laser beams.

Consistent with the present disclosure, a controller may be included forprocessing and/or analyzing collected data for various operations. Forexample, the controller may process received signals and control anyoperations based on the processed signals. The controller may alsocommunicate with a remote computing device, such as a server (or anysuitable cloud computing system) for operations of LiDAR system 102.Components of the controller may be in an integrated device ordistributed at different locations but communicate with one anotherthrough a network. In some embodiments, the controller may be locatedentirely within LiDAR system 102. In some embodiments, one or morecomponents of the controller may be located in LiDAR system 102, insidevehicle 100, or may be alternatively in a mobile device, in the cloud,or another remote location.

In some embodiments, the controller may process the received signallocally. In some alternative embodiments, the controller is connected toa server for processing the received signal. For example, the controllermay stream the received signal to the server for data processing andreceive the processed data (e.g., laser emission scheme(s) forcontrolling the laser power in an aperture) from the server. In someembodiments, the received signal is processed and the laser emissionscheme(s) may be generated in real-time. A distance between the objectand LiDAR system 102 may be updated in real-time for the determinationof the laser emission scheme(s).

FIG. 2A illustrates a block diagram of an exemplary implementation ofLiDAR system 102, according to embodiments of the disclosure. As shownin FIG. 2A, LiDAR system 102 has a transmitter 202 for emitting a laserbeam 209 and a receiver 204 for collecting data that include a returnedlaser beam 211 reflected by an object 212. Transmitter 202 may includeany suitable light source that emits laser beam 209 outwardly into thesurroundings of LiDAR system 102. In some embodiments, laser beam 209includes a pulsed laser signal with a scanning angle, as illustrated inFIG. 2A.

Transmitter 202 may include any suitable components for generating laserbeam 209 of a desired wavelength and/or intensity. For example,transmitter 202 may include a laser source 206 that generates a nativelaser beam 207 in the ultraviolet, visible, or near infrared wavelengthrange. Transmitter 202 may also include a light modulator 208 thatcollimates native laser beam 207 to generate laser beam 209. Scanner 210can scan laser beam 209 at a desired scanning angle and a desiredscanning rate. Each laser beam 209 can form a scanning point on asurface facing transmitter 202 and at a distance from LiDAR system 102.Laser beam 209 may be incident on object 212, reflected back, andcollected by a lens 214. Object 212 may be made of a wide range ofmaterials including, for example, live objects, non-metallic objects,rocks, rain, chemical compounds, aerosols, clouds and even singlemolecules. The wavelength of laser beam 209 may vary based on thecomposition of object 212. In some embodiments of the presentdisclosure, scanner 210 may include optical components (e.g., lenses,mirrors) that can focus pulsed laser light into a narrow laser beam toincrease the scan resolution.

Receiver 204 may be configured to detect returned laser beam 211 (e.g.,returned signals) reflected from object 212. Upon contact, laser lightcan be reflected by object 212 via backscattering, such as Rayleighscattering, Mie scattering, Raman scattering, and fluorescence. Receiver204 can collect returned laser beam 211 and output electrical signalindicative of the intensity of returned laser beam 211. As illustratedin FIG. 2A, receiver 204 may include lens 214 and a photodetector (orphotodetector array) 216. Lens 214 may be configured to collect lightfrom a respective direction in its field of view (FOV).

Photodetector 216 may be configured to detect returned laser beam 211reflected by object 212. Photodetector 216 may convert the laser light(e.g., returned laser beam 211) collected by lens 214 into a receiversignal 218 (e.g., a current or a voltage signal). Receiver signal 218may be generated when photons are absorbed in photodiode 216. Receiversignal 218 may be transmitted to a data processing unit, e.g.,controller 252 of LiDAR system 102, to be processed and analyzed.Controller 252 may be configured to control transmitter 202 and/orreceiver 204 to perform detection/sensing operations.

Receiver signal 218 may include the power data (e.g., an electricalsignal) of returned laser beam 211, e.g., converted from the lightsignal of returned laser beam 211. Returned laser beam 211 may be causedby the reflection of laser beam 209 from object 212 in the FOV of LiDARsystem 102. As shown in FIG. 2A, scanner 210 may emit/scan laser beam209 in various directions towards the surroundings. Laser beam 209 maybe incident on object 212 to cause returned laser beam 211 to be formedand reflected back toward LiDAR system 102. Photodetector 216 mayreceive returned laser beam 211 through lens 214. Photodetector 216 mayconvert returned laser beam 211 into electrical signal 218, which istransmitted to controller 252. Controller 252 may further determine dataand/or operations such as the distance of object 212 from LiDAR system102 and subsequent laser emission scheme(s) of laser beam 209.

To obtain a desired coverage of the surroundings and/or the resolutionof the scanning/sensing result, the power of laser beam 209 can becontrolled/adjusted. For example, the power of laser beam 209 needs tobe sufficiently high for LiDAR system 102 to detect object 212 from adesired distance. The span of the scanning angles of laser beam 209,e.g., in the three-dimensional (3D) space, also needs to be sufficientlylarge to cover a desired range of the surroundings laterally andvertically. Scanner 210 may scan laser beam 209 in the 3D space along alateral scanning direction and a vertical scanning direction, e.g., fromleft to the right and from top to bottom, at a desired scanning rate.

Controller 252 may determine the distance of object 212 from LiDARsystem 102 based on receiver signal 218 and data of laser beam 209. Forexample, the distance between object 212 and LiDAR system 102 may becalculated based on the speed of light, the scanning angle of laser beam209, the round-trip travel time of laser beam 209/211 (e.g., fromtransmitter 202 to object 212 and back to receiver 204), and/or thepower of returned laser beam 211 (e.g., the intensity of the lightsignal converted by photodetector 216 to receiver signal 218).Controller 252 may sense object 212 and adjust the laser emission schemeof laser beam 209 when the distance between object 212 and LiDAR system102 is equal to or less than a distance tolerance value (e.g., adistance at which unadjusted laser beam 209 in subsequent emissionswould cause potential harm when object 212 is a human being or possessessafety concerns). For example, to reduce or avoid the potential harm tohuman eyes, the laser emission scheme, after the adjustment, can causethe total power incident on an area representative of the size of ahuman pupil at the distance to be lower than a safety limit. In someembodiments, the adjustment of laser emission scheme is performed inreal-time or near real-time. For example, if the distance between object212 and LiDAR system 102 changes, controller 252 may dynamically adjustthe laser emission scheme to ensure the total power incident on the areaat the changed distance is less than the safety limit. For example, ifthe distance decreases, controller 252 may adjust the laser emissionscheme so that the total power to be incident on the area does notexceed the safety limit. Functions of controller 252 for thedetermination of the distance or other triggers related to the potentialharm and the adjustment of laser emission scheme of laser beam 209 aredescribed in greater detail in connection with FIG. 2B.

FIG. 2B shows an exemplary implementation of controller 252, accordingto embodiments of the disclosure. Consistent with the presentdisclosure, controller 252 may receive receiver signal 218 (e.g.,containing power data of returned laser beam 211) from photodetector216.

In some embodiments, as shown in FIG. 2B, controller 252 may include acommunication interface 228, a processor 230, a memory 240, and astorage 242. In some embodiments, controller 252 may have differentmodules in a single device, such as an integrated circuit (IC) chip(implemented as, for example, an application-specific integrated circuit(ASIC) or a field-programmable gate array (FPGA)), or separate deviceswith dedicated functions. In some embodiments, one or more components ofcontroller 252 may be located in a cloud, or may be alternatively in asingle location (such as inside vehicle 100 or a mobile device) ordistributed locations. Components of controller 252 may be in anintegrated device, or distributed at different locations but communicatewith each other through a network.

Communication interface 228 may send data to and receive data fromcomponents such as photodetector 216 via communication cables, aWireless Local Area Network (WLAN), a Wide Area Network (WAN), wirelesscommunication links such as radio waves, a cellular network, and/or alocal or short-range wireless network (e.g., Bluetooth™), or othercommunication methods. In some embodiments, communication interface 228can be an integrated services digital network (ISDN) card, cable modem,satellite modem, or a modem to provide a data communication connection.As another example, communication interface 228 can be a local areanetwork (LAN) card to provide a data communication connection to acompatible LAN. Wireless links can also be implemented by communicationinterface 228. In such an implementation, communication interface 228can send and receive electrical, electromagnetic or optical signals thatcarry digital data streams representing various types of information.

Consistent with some embodiments, communication interface 228 mayreceive receiver signal 218 (e.g., containing data of returned laserbeam 211). In some embodiments, communication interface 228 maysequentially receive receiver signals 218 as scanner 210 continues toscan laser beams 209 at the scanning rate. Communication interface 228may transmit the received receiver signal 218 to processor 230 forprocessing.

Processor 230 may include any appropriate type of general-purpose orspecial-purpose microprocessor, digital signal processor, ormicrocontroller. Processor 230 may be configured as a stand-aloneprocessor module dedicated to analyzing signals (e.g., receiver signal218) and/or controlling the scan schemes. Alternatively, processor 230may be configured as a shared processor module for performing otherfunctions unrelated to signal analysis/scan scheme control.

In many LiDAR systems with laser wavelengths between 800 nm and 900 nm,or shorter than 1400 nm, laser energy is strictly regulated due to itspotential damage to human eyes. Traditionally, the energy of each laserpulse is set to be within the regulation/safety limit, based on theassumption or worst case scenario that all pulses emitted towards a 7 mmpupil-size aperture is absorbed by the aperture. For high resolution andlong-range LiDAR systems, this becomes a fundamental challenge. First,high resolution LiDAR may transmit more pulses with small spatial stepsize, which means 10 or more pulses would be inside the 7 mm pupil areaat close distance, forcing each pulse to be lower energy. Also, longdistance LiDAR requires high energy pulses, which is difficult or evenimpossible to achieve with the power limit set by the regulation.

The present disclosure provides systems and methods for dynamicallyreducing the scanning energy at an object when the object is in a shortdistance from the LiDAR system. The LiDAR system (e.g., via thecontroller) may adjust the laser emission scheme dynamically as thedistance changes to ensure the total laser power to be incident on apupil-size aperture, which represents a human pupil, does not exceed apredetermined tolerance value. The human pupil is thus less susceptibleto harm caused by the LiDAR system. Details of the embodiments aredescribed in greater detail as follows.

As shown in FIG. 2B, processor 230 may include multiple functional unitsor modules that can be implemented using software, hardware, middleware,firmware, or any combination thereof. For example, processor 230 mayinclude an object detecting unit 238, a transmitter adjusting module250, or the like. In some embodiments, transmitter adjusting module 250includes a transmitter power control unit 232, a transmitter pulsingcontrol unit 234, and a transmitter scan control unit 236. In someembodiments, processor 230 compares a total power of laser beam 209 tobe incident on object 212, e.g., in a pupil-sized aperture, with apredetermined tolerance value. The predetermined tolerance value may beequal to or be correlated with the safety limit, over which potentialharm can be caused to human eyes by laser beam 209. Processor 230 mayalso adjust the laser emission scheme so that the total power of laserbeam 209 in the aperture does not exceed the predetermined tolerancevalue. Thus, if object 212 is indeed a human being, the human eyes areless susceptible to harm caused by laser beam 209.

Object detecting unit 238 may determine whether object 212 is subjectedto potential harm by laser beam 209 and send an alert signal totransmitter adjusting module 250 after determining that object 212 issubjected to potential harm. Transmitter adjusting module 250 may adjustthe laser emission scheme accordingly. In some embodiments, objectdetecting unit 238 also sends to transmitter adjusting module 250 anydata that can be used for the adjustment of laser emission scheme, suchas the distance between object 212 and LiDAR system 102. In someembodiments, object detecting unit 238 determines object 212 is in theFOV of LiDAR system 102 based on receiver signal 218. Object detectingunit 238 may determine the distance between object 212 and LiDAR system102 based on, e.g., the round-trip travel time of laser beams 209 and211 and the scanning angle of scanner 210.

Object detecting unit 238 may compare, e.g., in real-time, the distancebetween LiDAR system 102 and object 212 with a distance tolerance value.For example, when the distance between LiDAR system 102 and object 212is greater than the distance tolerance value, it may be determined thatno harm can be caused by laser beam 209. On the other hand, when objectdetecting unit 238 determines that the distance between LiDAR system 102and object 212 is equal to or less than the distance tolerance value,object detecting unit 238 may send an alert signal to transmitteradjusting module 250. The distance tolerance value may be a suitablevalue that is determined based on, for example, the maximal or ratedpower of laser beam 209, the spatial steps of the scanning angles, thedensity of the scanning angles, the number of pulses per scanning angle,and/or the safety limit imposed by the relevant regulations to protecthuman eyes.

After receiving the alert signal, the distance between object 212 andLiDAR system 102, and/or other relevant data, transmitter adjustingmodule 250 may further determine a value indicating the total power tobe incident on an aperture (e.g., a pupil-sized aperture) at thedistance in subsequent laser emissions if a current laser emissionscheme remains unchanged. Based on the value, transmitter adjustingmodule 250 may adjust the laser emission scheme so that the total laserpower to be incident on the aperture in subsequent laser emissions doesnot exceed the predetermined tolerance value with the adjusted laseremission scheme. The value indicating the total laser power to beincident on the aperture can be determined in various ways. In someembodiments, transmitter adjusting module 250 may determine the valuebased on the number of scanning points covered by the aperture at thedistance. In some embodiments, transmitter adjusting module 250 maydetermine the value based on a density of the scanning points at thedistance. In some embodiments, transmitter adjusting module 250 maydetermine the value based on a size of a scanning point at the distance.In some embodiments, the value may include the total power of laser beam209 incident to the aperture, which can be calculated based on anysuitable combinations of the above-mentioned quantities or similar data.In some embodiments, transmitter adjusting module 250 may incorporatesuitable existing data (e.g., stored in memory 240 and/or storage 242)of laser beam 209 for the calculation of total power of laser beam 209.For example, transmitter adjusting module 250 may employ data ofscanning rate, scanning angle, angle between adjacent laser beams 209,and/or power of laser beam 209 (e.g., a single laser beam 209) for thecalculation of the total power. In some embodiments, instead ofcalculating the total power, transmitter adjusting module 250 mayinstead use any of the number of scanning points covered by the apertureat the distance, the density of the scanning points at the distance, orthe size of the scanning point at the distance as indicator(s) (e.g.,the value) of the total power, and may determine whether the total powerexceeds the predetermined tolerance value based on the indicator(s). Forexample, a look-up table can be used to mapping the relationship betweenthe indicator(s) and the corresponding indicator(s) that represent thepredetermined tolerance value. In another example, instead of or inaddition to using a look-up table, the relationship can also becalculated in a dynamic or on-demand manner. In some embodiments, one ormore operations, or portions thereof, described above as being performedby transmitter adjusting module 250 may be performed by object detectingunit 238.

After determining the value indicating the total power of laser beam209, transmitter adjusting module 250 may compare the value with apredetermined tolerance value, which can be based on the safety limit oflaser power that can be incident on a human pupil. For example, thepredetermined tolerance value may be represented as a power valueindicating the maximal total power of laser light that can be incidenton a human pupil without causing harm. In another example, thepredetermined tolerance value may be represented as the maximal numberof scanning points that fall with a pupil-size aperture at a particulardistance for the kind of laser beam used for scanning. In a furtherexample, the predetermined tolerance value may be represented as adensity level at a particular distance. In yet a further example, thepredetermined tolerance value may be represented as a size of thescanning point at a particular distance. The predetermined tolerancevalue may also be represented using other indicators indicating themaximal total power of laser light that can be incident on a human pupilwithout causing harm. In some embodiments, comparison between the valueand the predetermined tolerance value may be performed by objectdetecting unit 238.

Transmitting adjusting module 250 may adjust the laser emission schemefor emitting subsequent laser beams based on the comparison between thevalue indicating the total power and the predetermined tolerance value.As used here, a laser emission scheme may include the manner ofscanning, such as skipping one or more scanning angles and adjusting theorder, sequence, and/or pattern of scanning. The laser emission schememay also include adjusting the power of the laser beam, such as reducingthe power of a laser beam to be emitted along a particular angle,reducing the power of one or more pulses of a multi-pulse laser beam, orskipping one or more pulses of a multi-pulse laser beam.

In some embodiments, when the comparison result indicates that the totalpower incident on the pupil-size aperture at the distance is greaterthan the safety limit, transmitting adjusting module 250 may adjust thelaser emission scheme to reduce the total power to a level below thesafety limit. In various embodiments, the adjustment can include one ormore methods. In some embodiments, transmitter power control unit 232reduces the power (e.g., peak power or intensity) of laser beam 209 atone or more scanning angles such that the total power carried by thescanning points covered by the aperture reduces. In some embodiments,transmitter pulsing control unit 234 reduces the number of pulses at ascanning point, e.g., in a multi-pulse ranging operation. In someembodiments, transmitter scan control unit 236 reduces the number ofscanning points, e.g., skipping laser beams 209 at one or more scanningangles such that the number of scanning points covered by the aperturereduces.

Units 232-238 (and any corresponding sub-modules or sub-units) andmodule 250 can be hardware units (e.g., portions of an integratedcircuit) of processor 230 designed for operation independently or withother components or software units implemented by processor 230 throughexecuting at least part of a program. The program may be stored on acomputer-readable medium. When the program is executed by processor 230,the executed program may cause processor 230 to perform one or morefunctions or operations. Although FIG. 2B shows units 232-238 all withinone processor 230, it is contemplated that these units may bedistributed among multiple processors located close to or remotely witheach other. The functions of units 232-238 and module 250 are describedin greater detail as follows in connection with FIGS. 3A-3D, 4A-4B, and5.

Memory 240 and storage 242 may include any appropriate type of massstorage provided to store any type of information that processor 230 mayneed to operate. Memory 240 and/or storage 242 may be volatile ornon-volatile, magnetic, semiconductor-based, tape-based, optical,removable, non-removable, or other type of storage device or tangible(i.e., non-transitory) computer-readable medium including, but notlimited to, a ROM, a flash memory, a dynamic RAM, a static RAM, a harddisk, an SSD, an optical disk, etc. Memory 240 and/or storage 242 may beconfigured to store one or more computer programs that may be executedby processor 230 to perform functions disclosed herein. For example,memory 240 and/or storage 242 may be configured to store program(s) thatmay be executed by processor 230 to analyze LiDAR signals and controlthe scanning schemes of laser beams.

Memory 240 and/or storage 242 may be further configured to store/cacheinformation and data received and/or used by processor 230. Forinstance, memory 240 and/or storage 242 may be configured to store/cachereceiver signal 218, data of laser beam 209, predetermined tolerancevalue(s), look-up tables storing mapping relationship between valuesindicating the total power incident to a pupil-size aperture at variousdistances and the corresponding tolerance values indicating the safetylimits, and calculation results obtained by different units of processor230. The various types of data may be stored permanently, removedperiodically, or disregarded immediately after each frame of data isprocessed.

FIG. 3A illustrates an exemplary FOV 300 of LiDAR system 102, accordingto embodiments of the present disclosure. FIG. 3B illustrates anexemplary laser emission scheme 352 at a location 302 of FOV 300,according to embodiments of the present disclosure. FIG. 3C illustratesan exemplary laser emission scheme 354 at a location 304 of FOV 300,according to embodiments of the present disclosure. FIG. 3D illustratesanother exemplary laser emission scheme 356 at location 302 of FOV 300,according to embodiments of the present disclosure. FIGS. 4A and 4Billustrate a plurality of laser emission schemes used in a multi-pulseranging operation. FIG. 5 illustrates a flow chart of an exemplarymethod 500 for controlling the scanning scheme of laser beam 209 tolimit its power based on the predetermined tolerance value, according tosome embodiments. For ease of illustration method 500 is described withFIGS. 3A-3D and 4A-4B, and the adjustment of laser emission scheme 352is used as an example to describe method 500.

At step 502, an object is detected based on a returned laser signal.Referring to FIG. 3A, the control/adjustment of laser emission schemefor an object 212-1 at location 302 is described for illustrativepurposes. Returned laser signal 211 may be formed by the reflection oflaser beam 209 from object 212-1. Controller 252 may receive respectivereceiver signal (e.g., 218) of returned laser signal 211 and determinethe existence of object 212-1 based on the receiver signal. In someembodiments, the intensity of the receiver signal from an object (e.g.,object 212-1) is different from the intensity of receiver signals whenno object is detected. For example, the intensity of the receiver signalmay be zero or a flat noise value when no object is detected, and theintensity of the receiver signal formed by the reflection of laser beam209 from object 212-1 may be a value significantly different from (e.g.,greater than) zero/noise value.

As shown in FIG. 3A, controller 252 may control transmitter 202 to scanlaser beam 209 along various directions/angles within FOV 300 of LiDARsystem 102. In some embodiments, transmitter 202 (e.g., via scanner 210)may scan laser beam 209 along a lateral scanning direction (e.g., thex-direction) and a vertical scanning direction (e.g., the y-direction).In an example, the scanning angle of laser beam 209 may include avertical scanning angle and a lateral scanning angle. The verticalscanning angle may represent the direction of laser beam 209 withrespect to the vertical direction (e.g., the y-direction), and thelateral scanning angle may represent the direction of laser beam 209with respect to a lateral direction (e.g., the x-direction). At a fixedlateral scanning angle, transmitter 202 may incrementally change thevertical scanning angle of laser beam 209 by a vertical delta angle soone laser beam 209 and an immediately-subsequent laser beam 209 may beseparated from each other by the vertical delta angle. The verticaldelta angle may be any suitable value such as 0.01°, 0.02°, 0.05°, 0.1°,0.2°, 0.5°, 1°, and the like. In some embodiments, transmitter 202 scanslaser beam 209 from top to bottom in the 3D space at each lateralscanning angle. After scanning laser beam 209 at one lateral scanningangle, transmitter 202 may scan laser beam 209 from top to bottom in the3D space at another lateral scanning angle, which may form a lateraldelta angle with the previous lateral scanning angle. The lateral deltaangle may be any suitable value such as 0.01°, 0.02°, 0.05°, 0.1°, 0.2°,0.5°, 1°, and the like.

In some embodiments, transmitter 202 repeatedly scans laser beam 209vertically and laterally to cover FOV 300. Laser beam 209 may be emittedalong its respective scanning direction within FOV 300 at the time it isbeing scanned. At any location in FOV 300, on a vertical plane facinglaser beam 209, the scanning pattern of laser beams 209 may form aplurality of scanning points, each scanning point corresponding to laserbeam 209 scanned or to be scanned at a given time. In other words, thelaser beams 209 emitted or to be emitted along a plurality angles mayproject to the vertical plane to form the plurality of projections,forming the plurality of scanning points. In some embodiments, at adesired scanning rate, transmitter 202 may scan laser beam 209 aplurality of times (e.g., at different vertical scanning angles) at onelateral scanning angle before moving to the next lateral scanning angle.In some embodiments, transmitter 202 may scan laser beam 209 a pluralityof times (e.g., at different lateral scanning angles) at one verticalscanning angle before moving to the next vertical scanning angle. Insome embodiments, the lateral scanning angle, the vertical scanningangle, the lateral delta angles, the vertical delta angles, the scanningrate, and/or divergence characteristics of laser beam 209 may be used todetermine the spatial/geometric distribution of laser beam 209 in the 3Dspace and the distribution of scanning points at any suitablesurface/location.

When object 212-1 enters FOV 300 of LiDAR system 102, laser beam 209 maybe incident on object 212-1 as transmitter 202 scans laser beam 209vertically and laterally. Laser beam 209 may be reflected, formingreturned laser beam 211 from object 212-1. Returned laser beam 211 maythen be detected by photodetector 216 and converted to the respectivereceiver signal, which is further transmitted to controller 252 forprocessing. Details of the laser emission scheme by transmitter 202 areillustrated in FIGS. 3A-3D.

As shown in FIGS. 3A-3D, transmitter 202 may sequentially scan laserbeam 209 along the vertical scanning direction and along the lateralscanning direction. On a surface facing transmitter 202 at each location(e.g., 302 or 304), laser beam 209 may sequentially form a plurality of(e.g., an array of) scanning points 310 when it is scanned sequentiallyonto the surface. For ease of description, each scanning point 310 isreferred to as being corresponding to a laser beam 209. For example, asshown in FIG. 3B, scanning point 310-2 (in dark gray shade) maycorrespond to laser beam 209 incident on object 212-1. Returned laserbeam 211 of laser beam 209 corresponding to scanning point 310-2 may bedetected for determining the existence of object 212-1. Scanning points310-4 (in medium gray shade) may correspond to laser beams 209 to beadjusted in response to the detection of object 212-1. Scanning points310-0 (in light gray shade) may correspond to laser beam 209 notincident on any object and/or not adjusted in response to the detectionof an object.

Referring to FIG. 5, at step 504, a distance between the detected objectand the LiDAR system is determined. Referring back to FIGS. 2B and 3A,controller 252 (e.g., using object detecting unit 238) may determine adistance D1 between object 212-1 and LiDAR system 102. Controller 252may determine D1 based on the round-trip travel time of laser beam 209and returned laser beam 211, as well as the speed of light. In someembodiments, controller 252 may also incorporate the scanning angle oflaser beam 209 in the calculation that determines D1.

In some embodiments, after controller 252 (e.g., using object detectingunit 238) determines distance D1 is equal to or less than the distancetolerance value, controller 252 (e.g., using transmitter adjustingmodule 250) may determine the value indicating the total power to beincident on an aperture at distance D1. Based on the value, controller252 may adjust the laser emission scheme accordingly. In someembodiments, object detecting unit 238 transmits an alert signal and/orthe detected distance (e.g., D1) to transmitter adjusting module 250when the detected distance is less than or equal to a safety distancevalue. The distance tolerance value may represent a safety distancebeyond which laser beam 209 would likely not cause harm to human eyes.In some embodiments, controller 252 determines the distance tolerancevalue by incorporating the scanning parameters of laser beam 209 such asscanning angles, vertical delta angles, lateral delta angles, scanningrate, divergence characteristics, and/or power of laser beam 209, incombination with the safety limit of laser power. Controller 252 maythen determine little or no harm can be caused to human eyes when object212 is beyond the distance tolerance value. No alert signal is thusgenerated, thus no adjustment to laser emission scheme is performed.When controller 252 determines distance D1 is equal to or less than thedistance tolerance value, an alert signal and/or the detected distancemay be transmitted from object detecting unit 238 to transmitter adjustmodule 250, so transmitting adjusting module 250 may perform suitablecalculation to determine the adjustment to the laser emission schemeapplied to subsequent laser emissions.

At step 506, a value indicating the total laser power to be incident onan aperture at the distance is determined. In some embodiments, thevalue may include the total laser power value. Referring to FIGS. 3B and3C, controller 252 may determine the total power to be incident on anaperture A of a desired diameter d0 on the surface at the distance D1(e.g., at location 302 in FIG. 3A). In various embodiments, diameter d0of aperture A can be determined based on, e.g., the size/dimensions ofan area on object 212 that need to be protected from potential harmcaused by laser beam 209. In some embodiments, dimensions of aperture Aare similar to the dimensions of a human pupil so that the total powerto be incident in aperture A can represent the total power that can beincident on a human pupil. The control/adjustment of power can thus moreprecisely prevent the total power incident on aperture A (or a humanpupil) from exceeding the predetermined tolerance value, ensuring thesafety of human eyes. In some embodiments, diameter d0 of aperture A isabout 7 mm.

Controller 252 may determine the total power to be incident on apertureA by employing suitable parameters such as scanning angles, verticaldelta angles, lateral delta angles, scanning rate, divergencecharacteristics, power of a single laser beam 209, and/or distance D1.In some embodiments, controller 252 determines the number of scanningpoints 310 covered by aperture A for the determination of the totalpower. For example, as shown in FIG. 3B, controller 252 may determinescanning point 310-2 to be the first scanning point covered by apertureA, and determine one or more scanning points 310-4 along the lateral andvertical scanning directions and overlapped (e.g., partially or fully)with aperture A to be covered by aperture A. Controller 252 may thusdetermine the distribution of scanning points 310 at distance D1 basedon one or more of the parameters to determine the number of scanningpoints 310 covered by aperture A. Controller 252 may then determine thetotal power to be incident on aperture A to be the sum of power emittedby the laser beams 209 corresponding to scanning points 310-2 and 310-4.

Controller 252 may also determine other values indicative of orcorrelated with the total power to be incident on aperture A. Thesevalues may be used as alternatives of or supplements to the total powerto be incident on aperture A, for the adjustment of laser emissionscheme. These values may be correlated to and/or vary as functions ofdistance D1, and may reflect the total power to be incident on apertureA at distance D1.

In some embodiments, controller 252 determines the density of scanningpoints at the distance as a value indicative of the total power to beincident on aperture A. For example, controller 252 may calculate thedensity of scanning points 310 at distance A based on parameters such asthe scanning angles, vertical delta angles, lateral delta angles, and/orlaser beam divergence characteristics. The density of scanning points310 may be defined as the number of scanning points 310 in a unit areaat a particular distance between object 212 and LiDAR system 102. Insome embodiments, the density of scanning points 310 is inverselyproportional to the distance (e.g., D1) between the object (e.g., 212-1)and LiDAR system 102.

In some embodiments, controller 252 determines the size (e.g., spot sizeor diameter d1) of scanning point 310 at the distance as a valueindicative of the total power to be incident on aperture A. For example,controller 252 may calculate the size of scanning point 310 at distanceD1 based on parameters such as the scanning angles, vertical deltaangles, lateral delta angles, and/or laser beam divergencecharacteristics. In some embodiments, the size of scanning points 310 isproportional to the distance (e.g., D1) between the object (e.g., 212-1)and LiDAR system 102.

At step 508, the value indicating the total laser power to be incidenton aperture A at the distance is compared with a predetermined tolerancevalue. In some embodiments, controller 252 (e.g., using transmitteradjusting module 250) compares the total power and/or the one or morevalues indicative of the total power determined in step 506 with arespective tolerance value. For example, the predetermined tolerancevalue may include one or more tolerance values each corresponding to atype of quantity.

In some embodiments, the predetermined tolerance value includes one ormore of a predetermined power tolerance value, a predetermined densitytolerance value, and a predetermined size value of scanning points 310,each representing a safety limit of the respective value. In someembodiments, the predetermined power tolerance value includes themaximum laser power that can be incident on aperture A at the distance(e.g., D1). Laser power higher than the predetermined power tolerancevalue may cause harm to human eyes by laser beam 209. In someembodiments, the predetermined density tolerance value includes themaximum density of scanning points 310 at the distance (e.g., D1).Density of scanning points 310 higher than the predetermined densitytolerance value may cause harm to human eyes by laser beam 209. In someembodiments, the predetermined size value includes the minimum size(e.g., diameter) of scanning points 310 at the distance (e.g., D1). Sizeof scanning point 310 less than the predetermined size tolerance maycause harm to human eyes by laser beam 209.

Controller 252 may compare, at distance D1, one or more of the totallaser power to be incident on aperture A, the density of scanning points310, and/or the size of scanning point 310 with the respectivepredetermined tolerance value, at step 508. In step 510, controller 252may determine whether the comparison result indicates the safety limitpreventing human eyes from being harmed by subsequent laser beams 209will be exceeded. For example, at distance D1, if the total laser poweris higher than the predetermined power tolerance value, the density ofscanning points is higher than the predetermined density tolerancevalue, and/or the size of scanning point 310 is less than thepredetermined size value, controller 252 may determine that the safetylimit will be exceeded if no adjustment is made to subsequent laseremission scheme. According, method 500 proceeds to step 512 along theYES branch following step 510, in which controller 252 may adjust thelaser emission scheme so that the total laser power to be incident onaperture A by subsequent laser emissions is not higher than thepredetermined power tolerance value.

At step 512, the laser emission scheme may be adjusted to reduce thetotal power to be incident on aperture A so that the total laser powerand/or the values indicative of the total power are each less than orequal to the respective predetermined tolerance values. Referring toFIG. 3B, the laser emission scheme of LiDAR system 102 may be adjustedso the total laser power emitted by laser beams 209 corresponding toscanning points 310-2 and 310-4 is not greater than the predeterminedpower tolerance value. The adjustment of laser emission scheme isexplained using the adjustment of total laser power as an example. Theadjustment of laser emission scheme using the adjustment of other valuesindicative of the total laser power may be similar and details areomitted herein.

The total power to be incident on aperture A may be adjusted in variousways through adjusting laser emission schemes. The laser emission schememay be determined at least partially based on the difference betweenlaser power of laser beam 209 at one scanning point (e.g., 310-2) andthe predetermined tolerance value. For example, if the power of laserbeam 209 (e.g., corresponding to scanning point 310-2) is sufficientlyhigh, controller 252 may adjust the laser emission scheme by skipping asufficient number of scanning points 310 (e.g., all of scanning points310-4) to ensure the total power to be incident on aperture A does notexceed the predetermined power tolerance value. In some embodiments, ifthe difference between the power of laser beam 209 (e.g., correspondingto scanning point 310-2) and the predetermined power tolerance value issufficiently large, transmitter 202 may scan laser beam 209 at one ormore scanning points 310-4 with full power or reduced power. In otherwords, depending on the difference between laser power of laser beam 209and the predetermined tolerance value, controller 252 may adjust thelaser emission scheme by reducing the power of laser beam 209 at one ormore scanning points 310-4 covered by aperture A, skipping scanning ofone or more scanning points 310-4 covered by aperture A, or acombination of the two operations. Controller 252 may determine thenumber of scanning points 310-4 to be skipped, the number of scanningpoints 310-4 corresponding to laser beam 209 with full and/or reducedpower, or a combination of the two operations.

In some embodiments, as shown in FIG. 3B, along the vertical scanningdirection and the lateral scanning direction, controller 252 may reducethe laser power of laser beams 209 corresponding to one or more scanningpoints 310-4 so that the total power emitted by laser beams 209corresponding to scanning points 310-2 and 310-4 is not greater than thepredetermined power tolerance value. In some embodiments, controller 252reduces the laser power of laser beams 209 corresponding to all scanningpoints 310-4 (e.g., eight scanning points 310-4) covered by aperture A.The laser power of laser beams 209 corresponding to scanning points310-4, after the adjustment/reduction, may be the same as or differentfrom one another. In some embodiments, controller 252 may skip scanning(e.g., not scanning laser beam 209 or emitting no laser power) of one ormore of scanning points 310-4. In some embodiment, controller 252 mayskip the scanning of laser beams 209 corresponding to all scanningpoints 310-4 (e.g., eight scanning points 310-4) covered by aperture A.

In some embodiments, power of laser beam 209 may not be adjustable ormay not be adjusted, and controller 252 may skip scanning of one or morescanning points 310-4 so that the total power incident on aperture Adoes not exceed the predetermined tolerance value. In some embodiments,the power of laser beam 209 is sufficiently high (e.g., higher than atleast one half of the predetermined power tolerance value such that morethan one laser beam emitted into aperture A would exceed the safetylimit) and controller 252 skips scanning of all scanning points 310-4 sothat the total power incident on aperture A does not exceed thepredetermined tolerance value.

In various embodiments, scanning point 310-2 can be located at any placewithin aperture A. The location of scanning point 310-2 in aperture A isnot limited to the upper left corner of aperture A, as shown in FIG. 3B.The goal of the laser emission scheme is to ensure that the total powerof scanning points falling within any aperture A (e.g., placed at anyplace against the scanning point pattern) is less than the predeterminedpower value. To that end, controller 252 may determine any suitabledistribution of scanning point 310-2 and scanning points 310-4 to meetthat goal.

In some embodiments, the distance tolerance value represents the minimumdistance between the object (e.g., 212-1) and LiDAR system 102. In otherwords, the power of laser beam 209 is sufficiently high (e.g.,sufficiently close to the predetermined power tolerance value) that thetotal power to be incident on aperture A can only include the laserpower at scanning point 310-2. Controller 252 may thus skip scanning oflaser beam 209 at all other scanning points (e.g., 8 scanning points310-2) when the distance between the object (e.g., 212-1) and LiDARsystem 102 is determined. In some embodiments, the distance tolerancevalue is determined based on the predetermined power tolerance value,the predetermined density tolerance value, and/or the predetermined sizetolerance value.

FIG. 3C illustrates another laser emission scheme 354 at location 304,according to embodiments of the present disclosure. As an example,distance D2 between object 212-2 at location 304 and LiDAR system 102 isgreater than distance D1 between location 302 and LiDAR system 102. Agreater distance (e.g., D2) can result in a different distribution ofscanning points 310 in the 3D space. For example, the size (e.g.,diameter d2) of scanning point 310 at distance D2 may be greater thanthe size of scanning point 310 at distance D1 and the density ofscanning points 310 at distance D2 may be less than the density ofscanning point 310 at distance D1.

Because D2 is greater than D1, the number of scanning points 310 coveredby aperture A at distance D2 is less than the number of scanning points310 covered by aperture A at distance D1. As an example shown in FIG.3C, four scanning points 310-2 and 310-4 are shown to be within apertureA. Controller 252 may adjust the laser emission scheme for scanninglaser beam 209 at distance D2 using similar or the same operations asthe operations for distance D1. Detailed description of the operationsof controller 252 may be referred to the description of FIGS. 3A and 3B,and is not repeated herein.

As an example, transmitter 202 may scan laser beam 209 from left toright in FOV 300 so object 212-2 is detected later than object 212-1.When both objects 212-1 and 212-2 are present, controller 252 may adjustthe laser emission scheme according to the object that is more likely tobe harmed by laser beams 209. For example, in the case shown in FIG. 3B,controller 252 may determine that skipping eight scanning points forevery powered scanning point will comply with the safety requirement,while in the case shown in FIG. 3C, skipping three scanning points forevery powered scanning point will suffice. Because the requirementimposed on the case shown in FIG. 3B is more stringent, controller 252may use the laser emission scheme determined based on the case shown inFIG. 3B for all subsequent laser emissions. Alternatively, controller252 may dynamically adjust the laser emission scheme according tospecific objects. For example, controller 252 may adopt one laseremission scheme for a set of scanning angles corresponding to object212-1, and adopt another laser emission scheme for another set ofscanning angles corresponding to object 212-2.

In some embodiments, the distance between object 212 and LiDAR system102 changes over time, and controller 252 dynamically adjusts the laseremission scheme to ensure the total power incident on the aperture(e.g., aperture A) does not exceed the predetermined power tolerancevalue. For example, within the distance tolerance value, if object 212moves from one location (e.g., 302) to another location (e.g., 304),controller 252 may dynamically adjust the laser emission scheme eachtime a new distance between object 212 and LiDAR system 102 isdetermined. If it is detected the distance between object 212 and LiDARsystem 102 is equal to or greater than the distance tolerance value,controller 252 may stop adjusting laser emission scheme and resume thelaser emission scheme before the adjustment, e.g., scanning laser beam209 at each scanning point 310.

Referring to FIG. 5, when the comparison result in step 510 indicatesthat a safety limit is not exceeded, method 500 proceeds to step 514along the NO branch. In step 514, controller 252 may maintain a currentlaser emission scheme without making adjustment.

FIG. 3D illustrates an expanded version of laser emission scheme 352shown in FIG. 3B, according to embodiments of the present disclosure.FIG. 3D shows a sequence of scanning points leading to the detection ofan object and adjusted laser emission scheme for subsequent laseremissions.

As shown in FIG. 3D, transmitter 202 may scan laser beam 209 along thevertical scanning direction and, after scanning a column in the verticaldirection, move one step along the lateral scanning direction and startscanning the next column. In one example, transmitter 202 may scan allscanning points 310-0 within the dashed-line box 310-1 (e.g., theprevious laser emission scheme) before reaching scanning point 310-2, atwhich point an object (e.g., object 212-1) is detected. Controller 252may, based on the distance between the object and LiDAR system 102,determine that adjustment to the previous laser emission scheme isneeded. The adjusted laser emission scheme skips all eight scanningpoints within aperture A1. The next scanning point corresponding to ato-be-emitted laser beam (a powered scanning point) is scanning point310-6, which is the first scanning point falling within an adjacentaperture A2, whereas all other scanning points within A2 are to beskipped. The powered and skipped scanning points in the subsequentsequence can be similarly determined, such as powered scanning point310-10 and skipped scanning points 310-12 within a next aperture A3, aswell as other similar combinations shown in FIG. 3D. In this way, nomatter where the aperture is placed, it is guaranteed that no more thantwo powered scanning points fall within a single aperture, therebylimiting the total power to be lower than the safety limit.

It is noted that the scanning sequence can be different from thevertical-then-lateral matter shown in FIG. 4D. Controller 252 can makeadjustment to the laser emission scheme in a similar manner to ensurethat the total power within an arbitrarily placed aperture is not higherthan the safety limit.

FIGS. 4A and 4B illustrate a plurality of laser emission schemes for amulti-pulse ranging operation, according to embodiments of the presentdisclosure. FIG. 4B is a continuation of FIG. 4A. In some embodiments,in the multi-pulse ranging operation, laser beam 209 corresponding to asingle scanning point 310 may include a sequence of laser pulses 402.Each laser pulse 402 may have a power intensity/amplitude of P0. Thenumber of laser pulses 402 may be greater than 1. Controller 252 mayadjust the laser emission scheme for laser beam 209 corresponding to anyscanning point 310 covered by a respective aperture. The laser emissionscheme of laser beam 209 before adjustment is illustrated as “beforescheme adjustment”, in which a plurality of pulses 402 is in a sequenceS. The laser emission schemes of laser beam 209 after adjustment isillustrated as “scheme adjustment 1-7”.

As shown in FIGS. 4A and 4B, to adjust (e.g., reduce) the power of laserbeam 209, controller 252 may reduce the number of pulses 402 in sequenceS (“scheme adjustment 1”), reduce the power of a portion of pulses 402to form one or more pulses 404 with a power intensity/amplitude of P1(“scheme adjustment 2”, P1<P0), or reduce the power of all pulses 404 topower intensity/amplitude of P1 (“scheme adjustment 3”). In someembodiments, the reduced power intensity/amplitude of multiple pulses404 may be different (e.g., not necessarily equal to P1). Controller 252may also reduce both the number of pulses and the power of each pulse insequence S (“scheme adjustment 4”), reduce the number of pulses and thepower of some (but not all) of the remaining pulse(s) in sequence S(“scheme adjustment 5”). Controller 252 may also control to emit onlyone pulse 402 in sequence S (“scheme adjustment 6”) or emit only onepulse with reduced power 404 in sequence S (“scheme adjustment 7”). Itshould be noted that, the laser emission schemes shown in FIGS. 4A and4B are merely examples to shown different combinations of pulses 402 and404 in sequence S, and are not meant to limit the order of pulse 402/404and/or values of P0/P1. For example, in a single sequence S, pulses 402and 404 may also be emitted in other orders/timing. Poweramplitude/intensity P1 of each pulse 404 may be the same as each otheror different from one another in the same sequence S or differentsequences.

Another aspect of the disclosure is directed to a non-transitorycomputer-readable medium storing instructions which, when executed,cause one or more processors to perform the methods, as discussed above.The computer-readable medium may include volatile or non-volatile,magnetic, semiconductor, tape, optical, removable, non-removable, orother types of computer-readable medium or computer-readable storagedevices. For example, the computer-readable medium may be the storagedevice or the memory module having the computer instructions storedthereon, as disclosed. In some embodiments, the computer-readable mediummay be a disc or a flash drive having the computer instructions storedthereon.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed system andrelated methods. Other embodiments will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosed system and related methods.

It is intended that the specification and examples be considered asexemplary only, with a true scope being indicated by the followingclaims and their equivalents.

1.-20. (canceled)
 21. An optical sensing device, comprising: atransmitter configured to scan a surrounding environment of the opticalsensing device using a plurality of laser beams; a receiver configuredto receive one or more reflected laser beams reflected from thesurrounding environment; and a controller coupled to the transmitter andthe receiver, wherein the controller is configured to: detect, based onthe one or more reflected laser beams received by the receiver, anobject in the surround environment; determine a distance between theobject and the optical sensing device; compare the distance with adistance tolerance value; and after determining that the distance isequal to or less than the distance tolerance value, control thetransmitter to reduce energy of one or more subsequent laser beams to beemitted to the surrounding environment.
 22. The optical sensing deviceof claim 21, wherein the controller is configured to: control thetransmitter to skip at least one subsequent laser beam to reduce theenergy of one or more subsequent laser beams to be emitted to thesurround environment.
 23. The optical sensing device of claim 22,wherein the controller is configured to: determine a number of laserbeams to be skipped based on the distance; and control the transmitterto skip the determined number of laser beams in subsequent laser beamemissions.
 24. The optical sensing device of claim 21, wherein thecontroller is configured to: control the transmitter to reduce power ofat least one subsequent laser beam to reduce the energy of one or moresubsequent laser beams to be emitted to the surround environment. 25.The optical sensing device of claim 24, wherein the at least onesubsequent laser beam comprises a sequence of laser pulses.
 26. Theoptical sensing device of claim 25, wherein the controller is configuredto: control the transmitter to skip one or more laser pulses in thesequence.
 27. The optical sensing device of claim 25, wherein thecontroller is configured to: control the transmitter to reduce power ofone or more laser pulses in the sequence.
 28. The optical sensing deviceof claim 21, wherein the controller is configured to: determine a valueindicating a total power of one or more laser beams to be incident on anaperture at the distance; compare the value with a predeterminedtolerance value; and after determining that the value is greater thanthe predetermined tolerance value, control the transmitter to reduce theenergy of one or more subsequent laser beams to be emitted to thesurrounding environment.
 29. The optical sensing device of claim 28,wherein the aperture has a size of a human pupil.
 30. A method ofcontrolling laser light emission by an optical sensing device, themethod comprising: scanning a surrounding environment of the opticalsensing device using a plurality of laser beams; receiving one or morereflected laser beams reflected from the surrounding environment;detecting, based on the received one or more reflected laser beams, anobject in the surround environment; determining a distance between theobject and the optical sensing device; comparing the distance with adistance tolerance value; and after determining that the distance isequal to or less than the distance tolerance value, reducing energy ofone or more subsequent laser beams to be emitted to the surroundingenvironment.
 31. The method of claim 30, comprising: skipping at leastone subsequent laser beam to reduce the energy of one or more subsequentlaser beams to be emitted to the surround environment.
 32. The method ofclaim 31, comprising: determining a number of laser beams to be skippedbased on the distance; and skipping the determined number of laser beamsin subsequent laser beam emissions.
 33. The method of claim 30,comprising: reducing power of at least one subsequent laser beam toreduce the energy of one or more subsequent laser beams to be emitted tothe surround environment.
 34. The method of claim 33, wherein the atleast one subsequent laser beam comprises a sequence of laser pulses.35. The method of claim 34, comprising: skipping one or more laserpulses in the sequence.
 36. The method of claim 34, comprising: reducingpower of one or more laser pulses in the sequence.
 37. The method ofclaim 30, comprising: determining a value indicating a total power ofone or more laser beams to be incident on an aperture at the distance;comparing the value with a predetermined tolerance value; and afterdetermining that the value is greater than the predetermined tolerancevalue, reducing the energy of one or more subsequent laser beams to beemitted to the surrounding environment.
 38. The method of claim 37,wherein the aperture has a size of a human pupil.
 39. A non-transitorycomputer-readable medium having instructions stored thereon, wherein theinstructions, when executed by at least one processor, cause the atleast one processor to perform a method for controlling laser lightemission by an optical sensing device, the method comprising: scanning asurrounding environment of the optical sensing device using a pluralityof laser beams; receiving one or more reflected laser beams reflectedfrom the surrounding environment; detecting, based on the received oneor more reflected laser beams, an object in the surround environment;determining a distance between the object and the optical sensingdevice; comparing the distance with a distance tolerance value; andafter determining that the distance is equal to or less than thedistance tolerance value, reducing energy of one or more subsequentlaser beams to be emitted to the surrounding environment.
 40. Thenon-transitory computer-readable medium of claim 39, wherein the methodcomprises: determining a value indicating a total power of one or morelaser beams to be incident on an aperture at the distance; comparing thevalue with a predetermined tolerance value; and after determining thatthe value is greater than the predetermined tolerance value, reducingthe energy of one or more subsequent laser beams to be emitted to thesurrounding environment.